What is the process of gas in plants?

Answer 1

The process of gas exchange in plants is known as photosynthesis. Animals let out carbon dioxide that the plants convert to oxygen.

Gaseous Exchange in PlantsIn the plants the gaseous exchange occurs through surface of leaves. Special apparatus called as stomata are present on the surface on the leaves and green stem, through which plants exchange gases like carbon dioxide and oxygen. Stomatal opening is affected by various environmental factors like temperature, humidity, wind speed etc and thus affecting the gaseous exchange.

In the roots of the plants the gaseous exchange occurs through pores called lenticles. The process of gaseous exchange occurs by the process of diffusion in these cases.

Mechanism of gaseous exchange in plants

Plants require less energy per unit mass than animals as they possess lower metabolic rates. They do not therefore need to maintain the high rates of gaseous exchange of the more complex animals, and rely on diffusion through spaces between the cells (intracellular air spaces). No special ventilation mechanisms exist. Flowering plants exchange gases by diffusion through pores called stomata in their leaves and on their green stems, or if the stems are woody, through cracks in the bark or slits called lenticels.

Gas exchange in leaves

Leaves are thin and have a large surface area, and so they are the main sites of gaseous exchange. Inside the leaf of dicotyledons, there is a spongy mesophyll with large air spaces which allow efficient diffusion. There are also especially large spaces around the stomata. Since the system relies on diffusion, water can diffuse out of the plant just as easily. It is obvious that even a small amount of water stress may reduce plant growth (and therefore yield if it is a crop plant). Plants have protective mechanisms whereby they can close their stomata if water is in short supply. This depends on the action of plant hormones, particularly abscisic acid.

The oxygen movements inside the plant are determined by the diffusion gradients that exist in the intercellular air spaces. In this way oxygen travels towards the cells and dissolves in the surface moisture of their walls. From here it passes by diffusion into the cells themselves. Carbondioxide leaves the plants by the same pathway but in the reverse direction. (Fig 1)

The entire process would have become more complex in the photosynthesizing plants. Here the oxygen is produced by the chloroplasts as a waste product of photosynthesis. The oxygen may be used up immediately in respiration by mitochondria contained in the same cell, and waste carbondioxide from respiration may be used by the chloroplasts for photosynthesis.